Electrical heating resistance.



F. M. FURBER.

ELECTRICAL HEATING RESISTANCE.

APPLICATION FILED APR. 16, 1914.

1 ,222, 1 96. Patented Apr. 10, 1917.

WT/VESSES //\/\/E/\/ 70R 5 M 4 f 6174 M v UNITED STATES PATENT OFFICE.

FREDERICK FURBER, REVERE, MASSACHUSETTS, ASSIGNOR TO UNITED SHOE MACHINERY COMPANY, OF PATERSON, NEW JERSEY, A CORPORATION OF NEW JERSEY.

Specification of Letters I'atent.

ELECTRICAL HEATING RESISTANCE.

Application filed April 16, 1914. Serial No. 832,268.

To all whom it may concern:

Be it known that I, FREDERICK M. FURBER, a citizen of the United States,,residing at Revere, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Electrical Heating Resistances, of which the following description, in connection with the accompanying drawings, is a specification, like reference characters on the drawings indicating like parts in the several figures.

This invention relates to electrical heating resistances or resistance units. It is broadly the object of the invention to increase the durability and improve the reliability of devices of this character.

In using the common types of resistance units to heat the tools vof certain machines, as for instance, in edge .setting machines used in the manufacture of boots and shoes to burnish the edge portion of the sole of a shoe, it is found that certain changes take place in the units, produced apparently by the rapid vibration to which they are subj ected, that causes them to break down after they have been used'only a very short time. More specifically, someof these changes consist in a partial disintegration of the insulating cores, causing. them to break or crumble, and a similar disintegration or crumbling of the insulating paste that frequently is used to keep the adjacent turns of.the resistance wire out of contact with each other. This crumbling of the paste allows the turns of wire to touch each other andshort-circuit the unit. It is also found that the resistance wire is very liable to break at an abrupt bend or turn in the wire, such for instance as those often made at the connection between the resistance wire and its terminals.

To overcome these defects and cure these ob jections constitutes an important object of the present invention.

The invention will be readily understood from the following description of a preferred embodiment thereof, reference being made to the accompanying drawings, in

which Figure 1 is a central, longitudinal, sectional view of a resistance unit embodying the invention;

Fig. 2 is a view similar to Fig. 1 of the upper part'of the unit with the terminals secured thereto in a different manner from that shown in Fig. 1;

Fig. 3 is a plan view showing a detail of construction; and v Fig. 4 is a fragmentary, sectional view of a part of the unit shown in Fig. 1 but on an enlarged scale.

The unit shown comprises a rod 2 providedavith heads 3 and 4, respectively, at its opposite ends, and a body 6 of insulating material having a. bore through which the rod 2 extends. At the opposite ends of the body 6 conducting collars 7 and 8, respectively, are mounted; and between each of these collars and the adjacent heads 3 and 4, insulating washers 9 and 10, respectively, are interposed. The collar 8 fits snugly on the rod 2 so that it is in electrical connection with it, but the collar 7 is provided with an aperture of considerably larger diameter than the-rod 2 and is held out of contact with the rod by means of an insulating collar 12 which is positioned in said aperture and encircles the rod. The collar 12 preferably is made of some noncombustible insulating material, such for instance as lava.

Preferably, the body 6 and washers 9 and 10 are made of mica. These parts may be assembled on the rod 2 by stringing a number of thin mica washers on the rod before the head 4 is secured thereto, to form the part 9; then placing the collars 7 and 12 on the rod, as above described; next stringing a large number of mica washers on to the rod to form the body 6; then placing the washer 8 in position; and finally building up the member 10 in the same manner that the part 9 was constructed. When these parts are first laid up in this manner they will be longer than in their final condition in which they are shown in Fig. 1; and consequently it is desirable, for the purpose of assembling them, either to use a rod of greater length than that shown in Fig. 1, or else to join temporarily to the rod 2 another rod of the same diameter to form a continuation ofit. After the parts have been built up inthe manner described, they are all compressed to the relative dimensions shown in Fig. 1 and the rod 2 may then be cut off to the required length, or its extension be removed if one has been used. The head 4 is next placed on the rod and the end of the rod is riveted over the head to hold it securely in this position. The heads 3 and 4 thus will maintain in their compressed condition all the parts of the unit above described.

The body 6 and washers 9 and 10 are next turned in a lathe to form on each of these parts a smooth, cylindrical surface, the washers 9 and 10 being left of greater diameter than the body 6, as indicated in Fig. 1. A helical groove or thread, like the thread of a machine screw or bolt, is then formed 'in the peripheral surface of the body 6 and the resistance wire 14 is wound on the body in the groove so formed. By this construction the resistance wire is embedded in the body 6 and the ridge between adjacent turns of the groove serves to hold the turns of the coil of wire 14 out of contact with each other. This arrangement avoids the use, either for the insulating body or for holding the turns of wire apart, of any substance or composition that is likely to disintegrate. The insulating body, or core, constructed in the manner just described has proved to be very substantial both mechanically and electrically.

In order to avoid any abrupt turns or bends of the resistance wire 14 in making its connection with theterminals, I prefer to connect the opposite ends of the coil of wire to the collars 7 and 8, respectively. For this purpose the collar 7 has formed therein a groove 16 which lies nearly parallel with the turns of the groove formed in the body 6 and forms practically a continuation of the last turn of this groove adjacent to the collar 7. This collar may be made of copper and the groove may be a saw cut. The surface of the collar is substantially flush with the surface of the body 6 and the groove, starting at the surface of the collar, deepens gradually (see Fig. 3) as it extends away from the insulating body 6. The wire 14 at the end of the coil adjacent to the collar 7 is carried smoothly into this groove and held therein while the edges of the groove are pounded down or peened over to secure the wire. The opposite end of the coil 14 is connected to the collar 8 in the same manner. By this arrangement the wire 14: is wound smoothly off the body 6 at the end of the coil on to the collar 7 and into the groove 16 without any abrupt turn or bend.

The unit also includes an outer metallic tubular shell 18, which is supported on the washers 9 and 10, and, since these washers are of larger diameter than the body 6, they support the shell out of contact with the resistance wire 14. The end of this shell adjacent to the head 4 is tapered so that, when it is forced on to the collars 9 and 10, the frictional engagement of the collar 10 with the tapered portion of the shell will hold the shell securely in place. Preferably, the shell mamas is long enough to extend beyond the heads 3 and 4 of the rod at each end of the unit; and the space between the ends of the shell and the washers 9 and 10, respectively, is filled in with an insulating composition, as indicated at 19 and 20, to cover the heads 3 and 4. One of the various asbestos insulating compositions in commercial use may be used for this purpose.

As above stated, one end of the coil 14: is connected to the collar 7 and the opposite end to the collar 8; and, since the latter collar is in electrical connection with the rod 2, the terminals for the unit may conveniently be connected to the rod and the collar 7, respectively. This connection may be made either by drilling laterally into the head 3 and the collar 7, as shown in Fig. 1, and connecting the terminals 22 and 24C, respectively, to these members, suitable slots being formed in the shell 18 to admit the terminals; or the head 3 and collar 7 may be drilled in a direction parallel to the rod 2, as indicated in Fig. 2, to receive the termi nals 22 and 24. In the latter case, it is also necessary to drill through the washer 9 and the head 3 to provide a passage for the terminal 24, this terminal, however, being insulated from the head 3 by .one or more insulating collars of the usual form.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a resistance unit, the combination of an insulating body, a rod supporting said insulating body over substantially its entire length, a conducting collar mounted on the rod at each end of the insulating body, a

tenuous resistance wire wound on the body and fastened to said collar without substantial bending, an insulating member having a substantially greater cross sectional area than said body mounted on each end of the rod outside the collar, and a member having a bore making-a close fit with said insulating members, enveloping said insulating members, collars and body, the collars and body being supported by said insulating members out of contact with said last named member.

2. In a resistance unit, the combination of a rod, an insulating body through which said rod extends, a member of insulating material mounted on said rod at each end of said body, heads on said rod near opposite ends of the unit to secure said body and members on the rod, a resistance wire wound on said body, a shell inclosing said body and extending at each end of the unit beyond the heads of said rod, said members being constructed to support said shell out of contact with the resistance wire on said body, and an insulating filling in each end of said shell covering said heads.

3. In a resistance unit, the combination of a rod, an insulating body on said rod, a metallic collar on said rod at each end of said body, heads on opposite ends of said rod, an insulating member mounted between each of said heads and the adjacent conducting collar, said heads serving to hold said body, collars and insulating members compressed tightly together, a resistance wire wound on said body and having its opposite ends con nected, respectively, to said metallic collars, terminals for said wire electrically connected, respectively, with said collars, and a metallic outer shell for said unit mounted on said insulating members and extending at each end of the unit beyond the heads of said rod, said shell being supported by said members out of contact with said wire.

4. In a resistance unit, the combination of a rod, a cylindrical insulating body encircling said rod and supported thereby, a resistance w'ire wound on said body, a conducting collar on said rod at each end of said body, said collars being connected, respectively, to the opposite ends of said resistance wire, one of said collars being in electrical connection with said rod and the other being electrically insulated from said rod, terminals for said resistance wire connected, respectively, to the latter collar and to said rod, heads on opposite ends of said rod, an insulating washer mounted between each of said heads and the adjacent collar, said washers being of larger diameter than said body, a metallic shell inclosing said body and extending at each end of the unit beyond the heads of said rod, said shell being supported by said insulating washers out of contact with said resistance wire, and an insulating filling in the ends of said shell covering the heads of said rod.

in the Patent Ofiice.

'[snan] Correction in Letters Patent No. 1,222,196.

5. In a resistance unit, the combination of a rod, mica washers strung on said rod to form an insulating body having a cylindrical exterior surface, heads on'said rod holding said washers compressed tightly between them, said body having a helical groove in its peripheral surface, a resistance wire wound in said groove, and a metallic collar at each end of said body with its surface substantially flush with the surface of said body, each of said collars having a groove formed therein that constitutes substantially a continuation of the groove of said body, and said wire being carried at the ends of said coil from the groove in the body into the grooves in the respective collars and secured therein.

6. A unit comprising a rod, an insulating core mounted on said rod, resistance wire wound on said core, and insulating members made of compressible material mounted on said rod, having a cross section substantially greater than that of said core with said wire wound thereon, in combination with a tube having a bore of substantially the same cross section as that of said insulating members and having a tapered portion, whereby when said unit is inserted in said tube, one of said insulating members will bind in said tapered portion and said insulating members will firmly support said unit with said resistance wire spaced apart from said tube.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

FREDERICK M. FURBER.

Witnesses:

J OHN H. MCCREADY, WILLIAM B. KING.

It is hereby certified that in Letters Patent No. 1,222,196, granted April 10, 1917, upon the application of Frederick MdFurber, of Revere, Massachusetts, for an improvement in Electrical Heating-Resistances, an error appears in the printed specification requiring correction as follows: Page 2, lines 105 and 109, claim 1, for the word collar read collars; and that the said Letters Patent; should be read with this correction therein that the same may confcz'mto the record of the Signed and sealed'this 31st day of July, A. D., 1917.

F. w. H. CLAY, Acting) Commissioner of Patents. 

